The present invention relates to equipment for the functional reeducation and orthopaedic treatment of the joints of the limbs of the human body.
The present invention is concerned more particularly with splints, said to be movable, in comparison with appliances of fixed structure which allow only the support or posture of a traumatised limb.
Movable splints known hitherto consist mainly of a supporting means, on which is mounted by means of a joint pin a structure, said to be movable, capable of receiving and supporting at least partially the limb to be mobilised, for the purpose of the functional reeducation of one of the joints of this limb. Means are provided, of course, between the movable structure and the limb, to ensure support and retention under requisite conditions of functionality.
To perform a passive mobilisation function, splints of the above-mentioned type have been equipped with a motorisation assembly which is generally interposed between the movable structure and the supporting means. Such a motorisation assembly provided in various forms usually brings into operation an electric motor responsible for actuating a screw jack, so that, as a result of either of its rotations, it can control the bending and stretching of the movable structure in relation to the support.
Splints of the above-mentioned type are commonly used either in the domestic environment or in the hospital environment and can be considered as making it possible to ensure an acceptable reeducation function.
It was found, however, that because of the arrangement of the motorisation assembly it was impossible to obtain a constant driving torque, whatever the bending/stretching angle of the movable structure in relation to the supporting means, and a speed of angular movement constant over the entire attainable bending/stretching range. Variations in the driving torque and in the speed must be considered as scarcely favorable, if not unfavorable, to functional reeducation under ideal conditions, in view of the fact that the mobilised joint is subjected to variable and excessively high loads in terms of speed or torque periodically and outside the reeducational load schedules which have to be imposed on it.
Furthermore, it was also found that the arrangement involving interposing the motorisation assembly between the movable structure and the supporting means resulted, for the same reasons of variations in torque and speed, in a transmission efficiency, if not poor, at least nowhere near the best possible, and that it was consequently necessary to oversize the motorisation assembly by adopting a motor of a power higher than that required.
A direct result of this constraint is the higher cost price and a bulk which sometimes opposes the mounting of such means on small-size splints, such as those for the direct reeducation of the wrist and ankle.
The object of the invention is to remedy the above-mentioned problem by providing a new reversible motorisation assembly of small bulk, designed to be quickly adaptable to all types of movable reeducation structures and making it possible to impose on at least one of the segments of a simple or complex movable structure a relatively constant speed of angular movement and a constant driving torque, whatever the bending/stretching angle of said segment.
The above-mentioned means make it possible to carry out reeducational work of the highest quality and to construct reeducational splints at lower cost than that of current splints.
To achieve the above-mentioned aims, the motorisation assembly according to the invention is characterised in that it comprises:
a housing fastened to the structure and mounted rotatably on the joint pin which is fixed to the support;
a large toothed ring immobilised on the pin;
an electric motor with two directions of rotation mounted in the housing;
a reduction mechanism mounted in the housing and interposed between the electric motor and the large toothed ring which it engages.
Another subject of the invention is a splint for mobilising at least one joint of a lower limb, comprising a movable structure on which is attached the motorisation assembly likewise connected to the support of said structure.